It’s no “Rain Man,” but the new romantic dramedy “Adam” paints a realistic picture of someone living with a development disorder and combines it with a sweet and gentle love story that is hard to resist even during its most mawkish moments.

Hugh Dancy (“Confessions of a Shopaholic”) gives a fine performance as Adam Raki, a 29-year-old man living a lonely life in Manhattan with a type of high-functioning autism called Asperger’s Syndrome. The disability causes Adam to feel anxious in social situations and affects certain aspects of his behavior.

When Adam’s father passes away, he is left to make it on his own and falls back into the comfort of his daily routine as a mechanical engineer for a toy company. It’s a perfect job for the introverted Adam who is able to keep to himself and tinker away with gadgets without being bothered.

Adam’s habitual lifestyle is given a little boost when he meets Beth Buchwald (Rose Byrne), a new girl who has moved into his apartment building and cautiously takes a liking to Adam’s oddities. Adam, an expert in all things space related, attempts to befriend her with his knowledge of astronomy and the theory of relativity. Beth is fairly interested, but seems more fascinated with his little idiosyncrasies (he takes things too literally, rambles, and can’t connect emotionally to people). He’s like a less self-pitying version of Zach Braff’s character in “Garden State.”

As their friendship and relationship blossom, Adam and Beth learn more about each other and what makes the other tick. While director/writer Max Mayer (“Better Living”) keeps his couple at the center of his cinematic universe for the majority of the picture, a secondary storyline about Beth’s father (Peter Gallagher) comes out of left field and burdens the picture with a family dynamic that just doesn’t fit into the framing of the story.

Still, Mayer does as satisfactory job with his two leads. He never lets Adam’s limitations become a one-note joke or easy way out of a difficult scene. As Adam and Beth continue their relationship, Mayer, while playing it a bit too safe in the narrative, allows them to develop their bond logically and without the stereotypical plot points you would see in other offbeat romances.

Who knew guys with Aspberger’s Syndrome were going to become the most dateable guys around? At least that’s what Dancy does with Adam and all his charms. With some inviting depth to the character, “Adam” is more than a movie about someone learning how to deal with his or her special needs.